Preparation of trichlorothiazole and intermediate

Abstract

Trichlorothiazole of the formula ##STR1## IS PREPARED BY REACTING 1,2,2,2-TETRACHLOROETHYL-ISOCYANIDEDICHLORIDE OF THE FORMULA ##STR2## WITH 1 TO 1.2 TIMES THE STOICHIOMETRIC AMOUNT OF SULFUR AT A TEMPERATURE OF ABOUT 150° TO 250° C, preferably about 170° to 230° C.

What is claimed is 
     
       1. A process for the preparation of trichlorothiazole of the formula ##STR9## comprising reacting 1,2,2,2-tetrachloroethyl-isocyanide-dichloride of the formula ##STR10## with sulfur at a temperature of about 150° to 250° C. 
     
     
       2. The process according to claim 1, wherein the reaction is carried out at a temperature of about 170° to 230° C. 
     
     
       3. The process according to claim 1, wherein the reaction is carried out with about 1 to 1.2 times the stoichiometric amount of sulfur. 
     
     
       4. 1,2,2,2-tetrachloroethyl-isocyanide-dichloride of the formula ##STR11## 
     
     
       5. The process for making 1,2,2,2-tetrachloroethyl-isocyanide-dichloride according to claim 4, which comprises reacting chloral-formamide with chlorine and a highly active inorganic acid chloride. 
     
     
       6. The process according to claim 5 wherein the highly active inorganic acid chloride is phosphorus pentachloride or a mixture of phosphorus trichloride and at least an equimolar amount of chlorine or thionylchloride containing an addition of 0.01 to 10% by volume of a lower alkyl substituted acid of a lower aliphatic carboxylic acid. 
     
     
       7. The process according to claim 5, including the further steps of adding sulfur dioxide to destroy any unconsumed phosphorus chlorides and then distilling to separate impurities.